Hi Joe,
The Twin is back together and running on a coil from a single! It starts and runs fairly easilly, but the power is not there, I reckon the spark is only going to one or other of the plugs, it finds the path of least resistance and jumps that spark. This was proved by taking one HT lead off while running, the lead would short against the chasis, but taking it off the plug resulted in no change to the engine speed/note at all.
So still looking for a working twin coil.
Hope the move went well, hope youv'e got a decent lawn, probably drier than Brum!